Historic Flyby: Comet to Zoom By Mars This Weekend

A comet will buzz Mars this Sunday (Oct. 19) in an epic encounter that has astronomers around the world tingling with excitement.
Comet Siding Spring, also known as C/2013 A1, will miss the Red Planet by just 87,000 miles (140,000 kilometers) at 2:27 p.m. EDT (1827 GMT) on Sunday. For comparison, the moon orbits Earth at an average distance of 239,000 miles (384,600 km).
While the comet won’t put on a show for skywatchers here on Earth, the fleet of robotic explorers at Mars will get an eyeful. They will study the comet, as well as any observable interactions between its shed particles and the thin Martian atmosphere.